Fingerprint recognizable touch sensor and display device including the fingerprint recognizable touch sensor

ABSTRACT

A touch sensor may include: a touch panel including a plurality of electrodes and a plurality of electrode pads respectively connected to the plurality of electrodes; a bonding layer disposed on and in contact with the plurality of electrode pads; and a printed circuit board including: an insulating layer including a first surface adjacent to the bonding layer and a second surface facing the first surface; a plurality of first bonding pads provided in a first region of the first surface of the insulating layer; a plurality of second bonding pads disposed on the second surface of the insulating layer; and a plurality of extension pads disposed on a second region different from the first region of the first surface of the insulating layer and respectively connected to the plurality of second bonding pads.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Korean Patent Application No.10-2020-0013302, filed on Feb. 4, 2020 in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein byreference in its entirety.

BACKGROUND 1. Field

Apparatuses and methods consistent with example embodiments relate to atouch sensor having a fingerprint recognition function and a displaydevice including the same.

2. Description of Related Art

A touch sensor is an input device that recognizes a location of atouched area or related information and transmits information about thelocation of the touched area to a system when a user touches the touchsensor with a finger etc. The touch sensor has advantages of beingsimple and convenient to use. A touch sensor may generally be of aresistive overlay type, an electromagnetic type, a capacitive overlaytype, etc., depending on the method of sensing a touched portion. Inparticular, a touch sensor of a capacitive overlay type has theadvantages of high transmittance, excellent durability, excellent touchresolution, and multi-touch capability. Touch sensors are applied tovarious electronic devices, such as automatic teller machines (ATMs),automatic ticket machines, and navigation devices, as well as mobiledevices, such as smartphones and tablet personal computers (PCs).

A touch sensor generally includes a sensing unit for sensing a user'sfinger or the like and a printed circuit board for driving the sensingunit. The sensing unit may have a structure including a plurality ofelectrodes arranged to cross each other. Also, the sensing unit mayinclude a plurality of traces extending from the plurality of electrodesand a plurality of electrode pads respectively electrically connected tothe plurality of traces. The printed circuit board may include a chipthat transmits a driving signal to the sensing unit, a plurality oftraces extending from the chip, and a plurality of bonding padsrespectively electrically connected to the plurality of traces. Theplurality of electrode pads included in the sensing unit respectivelycontact the plurality of bonding pads included in the printed circuitboard, and thus, the sensing unit and the printed circuit board may beelectrically connected to each other.

In the related art, a pitch between the plurality of bonding padsincluded in the printed circuit board is in a range of about 100 μm toabout 150 μm. When a pitch between the bonding pads is 100 μm or less, ashort circuit may occur between the bonding pads and the electrode pads,thereby increasing a defect rate in a manufacturing process. Recently,the demand for touch sensors having a large area has rapidly increased.For a large area touch sensor, a pitch between the bonding pads shouldbe reduced because, when an area of a touch sensor is increased, therequired number of bonding pads increases, and a space where the bondingpads are provided is limited. Accordingly, there is a need for a printedcircuit board including a bonding pad having a narrow pitch (finepitch).

SUMMARY

Provided are fingerprint recognizable touch sensors including a printedcircuit board including a bonding pad having a small pitch and a displaydevice including the fingerprint recognizable touch sensors.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments of the disclosure.

According to an aspect of an example embodiment, there is provided atouch sensor including: a touch panel including a plurality ofelectrodes and a plurality of electrode pads respectively connected tothe plurality of electrodes; a bonding layer disposed on and in contactwith the plurality of electrode pads; and a printed circuit boardincluding: an insulating layer including a first surface adjacent to thebonding layer and a second surface facing the first surface; a pluralityof first bonding pads provided in a first region of the first surface ofthe insulating layer; a plurality of second bonding pads disposed on thesecond surface of the insulating layer; and a plurality of extensionpads disposed on a second region different from the first region of thefirst surface of the insulating layer and respectively connected to theplurality of second bonding pads.

On a plan view of the printed circuit board, the plurality of firstbonding pads and the plurality of second bonding pads may be alternatelyarranged in a first direction.

The first region and the second region may be separated from each otherbased on a center line that is parallel to the first direction on asurface of the insulating layer.

The plurality of first bonding pads and the plurality of extension padsmay be arranged in a zigzag shape with respect to the center line.

On the plan view of the printed circuit board, the plurality of secondbonding pads and the plurality of extension pads may be located on asame line in a second direction that is perpendicular to the firstdirection.

The plurality of second bonding pads may be included in all regionscorresponding to the first region and the second region.

The insulating layer may include a plurality of vias that connect theplurality of second bonding pads in a one-to-one correspondence to theplurality of extension pads.

The plurality of vias may be disposed on an edge of the second region ofthe insulating layer.

The plurality of vias may be disposed on an edge separated from aboundary line where the first region and the second region contact eachother with the plurality of extension pads therebetween.

The plurality of vias may be filled with a conductive material.

The plurality of electrode pads may be disposed on a same plane.

The plurality of electrode pads may be arranged to be parallel to eachother in the first direction.

The plurality of electrode pads are arranged in a zigzag shape based ona center line that is parallel to the first direction.

On the plan view of the printed circuit board, a separation distancebetween the first bonding pads and the second bonding pads adjacent toeach other is in a range of 15 μm to 35 μm.

The bonding layer may include an anisotropic conductive film layer.

The bonding layer may include a first bonding layer and a second bondinglayer that are separated from each other, wherein the first bondinglayer may be disposed between the plurality of first bonding pads andthe plurality of electrode pads, and the second bonding layer may bedisposed between the plurality of extension pads and the plurality ofelectrode pads.

The printed circuit board may include either one or both of a chip onfilm (COF) and a flexible printed circuit board (FPCB).

The plurality of electrodes and the plurality of electrode pads may bearranged on a substrate including at least one of glass and film.

The plurality of electrodes may include: a plurality of first electrodesextending in a first direction and arranged to be parallel to each otherin a second direction perpendicular to the first direction; and aplurality of second electrodes extending in the second direction tocross the plurality of first electrodes and disposed to be parallel toeach other in the first direction.

According to an aspect of another example embodiment, there is provideda display device including: the touch sensor; and a display paneldisposed on a lower side of the touch panel.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects will be more apparent by describingcertain example embodiments, with reference to the accompanyingdrawings, in which:

FIG. 1 is a lateral cross-sectional view showing a brief structure of atouch sensor according to an example embodiment;

FIG. 2 is a plan view showing a brief structure of a touch panel and aprinted circuit board included in the touch sensor according to anexample embodiment of FIG. 1;

FIG. 3 is a perspective view briefly showing an enlarged area C of FIG.1;

FIG. 4 is a lateral cross-sectional view briefly showing a cross-sectiontaken along the center line Lc1 of FIG. 1;

FIG. 5 is a plan view briefly showing an example configuration of anelectrode pad unit that may be included in the touch panel of FIG. 1;

FIG. 6 is a lateral cross-sectional view briefly showing an exampleconfiguration of the sensing unit of FIG. 1;

FIG. 7 is a lateral cross-sectional view briefly showing an exampleconfiguration of the sensing unit of FIG. 1, according to anotherexample embodiment; and

FIG. 8 is a lateral cross-sectional view schematically showing anexample configuration of a display device according to an exampleembodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings, wherein like referencenumerals refer to like elements throughout. In this regard, the presentembodiments may have different forms and should not be construed asbeing limited to the descriptions set forth herein. Accordingly, theembodiments are merely described below, by referring to the figures, toexplain aspects. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items. Expressionssuch as “at least one of,” when preceding a list of elements, modify theentire list of elements and do not modify the individual elements of thelist.

Hereinafter, a fingerprint recognizable touch sensor and a displaydevice including the fingerprint recognizable touch sensor according tovarious example embodiments will be described in detail with referenceto the accompanying drawings. In the drawings, like reference numeralsrefer to like elements, and size or thickness of each constitutingelement may be exaggerated for clarity of descriptions.

It will be understood that, although the terms “first”, “second”, etc.may be used herein to describe various elements, the elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another element. A fingerprint recognizable touch sensorand a display device including the same may be implemented in variousdifferent forms and are not limited to the example embodiments describedherein.

It should be understood that, when a part “comprises” or “includes” anelement in the specification, unless otherwise defined, other elementsare not excluded from the part and the part may further include otherelements

FIG. 1 is a lateral cross-sectional view showing a brief structure of atouch sensor 1000 according to an example embodiment. FIG. 2 is a planview showing a brief structure of a touch panel 100 and a printedcircuit board 300 included in the touch sensor 1000 of FIG. 1.

Referring to FIG. 1, the touch sensor 1000 may include the touch panel100 including a structure in which a sensing unit 110 and a plurality ofelectrode pads 10 are provided on a substrate sub. Referring to FIG. 2,the sensing unit 110 may include a plurality of electrodes Tx and Rx.The plurality of electrode pads 10 may be electrically connected to theplurality of electrodes Tx and Rx. A region where the plurality ofelectrode pads 10 are formed may be referred to as an electrode pad unit120. Also, the touch sensor 1000 may include a bonding layer 200 that iselectrically connected to the plurality of electrode pads 10. Forexample, the bonding layer 200 may be formed to contact the plurality ofelectrode pads 10.

Furthermore, the touch sensor 1000 may include the printed circuit board300 that is electrically connected to the touch panel 100 via thebonding layer 200. The printed circuit board 300 may include aninsulating layer 50 including a first surface 50 a adjacent to thebonding layer 200 and a second surface 50 b facing the first surface 50a. The printed circuit board 300 may include a plurality of firstbonding pads 20 provided in a first region A1 of the first surface 50 a.The printed circuit board 300 may include a plurality of second bondingpads 30 provided on the second surface 50 b. The printed circuit board300 may include a plurality of extension pads 40 that are provided on asecond region A2 different from the first region A1 of the first surface50 a and is connected to a plurality of second bonding pads 30. Forexample, the plurality of electrode pads 10 of the touch panel 100 andthe first bonding pads 20 and the extension pads 40 of the printedcircuit board 300 may be electrically connected via the bonding layer200. For example, the first bonding pad 20 and the extension pad 40 maycontact the other surface facing the surface of the bonding layer 200contacting the plurality of electrode pads 10. Accordingly, the firstbonding pad 20 and the extension pad 40 may be provided to be separatedfrom the plurality of electrode pads 10 with the bonding layer 200therebetween.

The touch panel 100 may include a sensing unit 110 that may sense acontact by a finger or an image of a fingerprint of a user etc. Thesensing unit 110 may include a plurality of first electrodes Tx and aplurality of second electrodes Rx. As illustrated in FIG. 2, theplurality of first electrodes Tx and the plurality of second electrodesRx may cross each other. For example, each of the plurality of firstelectrodes Tx may extend in a first direction (x-axis direction) and maybe repeatedly arranged to be parallel to each other in a seconddirection (y-axis direction) crossing the first direction (x-axisdirection). Also, each of the plurality of second electrodes Rx mayextend in the second direction (y-axis direction) so as to intersecteach of the plurality of first electrodes Tx and may be repeatedlyarranged to be parallel to each other in the first direction (x-axisdirection). As described above, since the plurality of first electrodesTx and the plurality of second electrodes Rx cross each other, thesensing unit 110 may include a mesh shape.

The sensing unit 110 may sense a touch, for example, by a capacitancemethod. In this case, a change in self-capacitance or mutual capacitanceis caused by a touch input or fingerprint input at nodes where theplurality of first electrodes Tx and the plurality of second electrodesRx cross each other, and thus, it is possible to calculate coordinatesof the touch input or an image of the touched fingerprint from thechange in the capacitance in the plurality of touched nodes.Accordingly, nodes where the plurality of first electrodes Tx and theplurality of second electrodes Rx cross each other may function aspixels sensing a touch input or a fingerprint input.

For example, a voltage may be applied to the plurality of firstelectrodes Tx or the plurality of second electrodes Rx from the outside.In this case, intersections of the plurality of first electrodes Tx andthe plurality of second electrodes Rx may have mutual capacitance. Whena user touches the sensing unit 110 with a finger, a change in mutualcapacitance may occur at intersections of the plurality of firstelectrodes Tx and the plurality of second electrodes Rx included in thetouched region. Coordinates of a touch input by the user may becalculated by measuring a change in mutual capacitance in the sensingunit 110.

Also, the change in the mutual capacitance may be different in anelectrode adjacent to a ridge and an electrode adjacent to a valley, theridge and the valley is indicated by a fingerprint on a surface of theuser's finger. A distance between the plurality of first electrodes Txand the plurality of second electrodes Rx may be formed to be less thanthat of the finger's ridge and valley. Accordingly, a change in themutual capacitance between the plurality of first electrodes Tx and theplurality of second electrodes Rx by a finger may be detected for eachlocation, and as a result, a fingerprint image may be calculated.

The plurality of first electrodes Tx may be driving electrodes thatreceive a voltage from the outside. In this case, the plurality ofsecond electrodes Rx may be sensing electrodes to which a measurementunit (e.g., a measurement circuit) capable of detecting a change inelectric capacity is connected. However, the present example embodimentis not limited thereto, that is, the plurality of second electrodes Rxmay be driving electrodes to which a voltage is applied from theoutside, and the plurality of first electrodes Tx may be sensingelectrodes to which a measuring unit capable of detecting a change inthe electric capacity is connected.

Referring to FIG. 2, the touch panel 100 may include a plurality oftraces Tr extending from the plurality of first electrodes Tx and theplurality of second electrodes Rx. The plurality of traces Tr may beconductive wirings. In other words, the plurality of traces Tr mayinclude a conductive material. For example, the plurality of traces Trmay include a transparent conductive material, such as indium tin oxide(ITO). The touch panel 100 may include the electrode pad unit 120 havinga plurality of electrode pads 10 connected to a plurality of firstelectrodes Tx and a plurality of second electrodes Rx. For example, theplurality of electrode pads 10 may be connected in one-to-onecorrespondence to the plurality of first electrodes Tx and the pluralityof second electrodes Rx through the plurality of traces Tr. Theplurality of electrode pads 10 may be arranged to be parallel to eachother in the first direction (x-axis direction). Two alignment marks Ak1may be provided in both ends of the electrode pad unit 120. For example,the two alignment marks Ak1 may be arranged to be separated from eachother with the plurality of electrode pads 10 arranged to be parallel toeach other in the first direction (x-axis direction) therebetween.

Referring to FIG. 1, the sensing unit 110 and the electrode pad unit 120electrically connected to each other by a plurality of traces Tr may beprovided on the substrate sub. In FIG. 1, for convenience ofdescription, the trace Tr is omitted. The substrate sub may betransparent. The substrate sub may include an insulating material. Forexample, the substrate (sub) may include polyethylene terephthalate(PET), polycarbonate (PC), polymethyl methacrylate (PMMA), polyethylenenaphthalate (PEN), polyethersulfone (PES), cyclic olefin polymer (COC),triacetylcellulose (TAC) film, polyvinyl alcohol (PVA) film, polyimide(PI) film, polystyrene (PS), biaxially oriented PS (BOPS), or glass. Inthis way, the substrate sub may include various materials, andaccordingly, may have various elongation percentages.

The bonding layer 200 may be a connection layer that electricallyconnects the touch panel 100 and the printed circuit board 300 to eachother. For example, the bonding layer 200 may include an anisotropicconductive film (ACF). The bonding layer 200 may be formed to contactthe plurality of electrode pads 10, the plurality of bonding pads 20,and the plurality of extension pads 40.

The printed circuit board 300 may include a bonding pad unit 310including the plurality of first bonding pads 20, the plurality ofsecond bonding pads 30, and the plurality of extension pads 40 providedon the insulating layer 50 and a microchip 320.

The bonding pad unit 310 may be electrically connected to the electrodepad unit 120 of the touch panel 100. The microchip 320 may generate adriving signal for driving the sensing unit 110 of the touch panel 100.The microchip 320 may be electrically connected to the bonding pad unit310. The driving signal from the microchip 320 may be transmitted to thebonding pad unit 310. The signal may be transmitted to the electrode padunit 120 electrically connected to the bonding pad unit 310. The drivingsignal finally transmitted to the electrode pad unit 120 may betransmitted to the plurality of first electrodes Tx or the plurality ofsecond electrodes Rx through the plurality of traces Tr. The printedcircuit board 300 may include any one of a chip on film (COF) and aflexible printed circuit board (FPCB). However, the present exampleembodiment is not limited thereto, that is, the printed circuit board300 may include any one of a tape carrier package (TCP) and a tapeautomated bonding (TAB).

Referring to FIG. 1, the bonding pad unit 310 may include the insulatinglayer 50. The insulating layer 50 may include a first surface 50 aadjacent to the bonding layer 200 and a second surface 50 b facing thefirst surface 50 a. For example, the first surface 50 a may be an uppersurface of the insulating layer 50 and the second surface 50 b may be alower surface of the insulating layer 50. The plurality of first bondingpads 20 may be provided on the first surface 50 a of the insulatinglayer 50. The plurality of second bonding pads 30 may be provided on thesecond surface 50 b of the insulating layer 50. The insulating layer 50may include polyimide (PI). However, the present example embodiment isnot limited thereto, that is, the insulating layer 50 may include otherinsulating materials other than polyimide (PI). The insulating layer 50may be provided between the plurality of first bonding pads 20 and theplurality of second bonding pads 30 to insulate the first and secondbonding pads 20 and 30 from each other.

Referring to FIG. 2, the plurality of first bonding pads 20 may bearranged to be parallel to each other in the first direction (x-axisdirection). Also, the plurality of second bonding pads 30 may bearranged to be parallel to each other in the first direction (x-axisdirection). Furthermore, the plurality of extension pads 40 may bearranged to be parallel to each other in the first direction (x-axisdirection). Two alignment marks Ak2 may be provided in both ends of thebonding pad unit 310. For example, the two alignment marks Ak2 may beseparated from each other with the plurality of first bonding pads 20,the plurality of second bonding pads 30, and the plurality of extensionpads 40 arranged to be parallel to each other in the first direction(x-axis direction) therebetween. Also, the two alignment marks Ak2 maybe provided on the center line Lc1 parallel to the first direction(x-axis direction) of the bonding pad portion 310.

When seen on a plan view of the printed circuit board 300 (z-axisdirection), the plurality of first bonding pads 20 and the plurality ofsecond bonding pads 30 may be alternately arranged with each other inthe first direction (x-axis direction). However, since the first bondingpads 20 and the second bonding pads 30 are provided on different layers,a short circuit may not substantially occur between the first bondingpads 20 and the second bonding pads 30.

Meanwhile, the plurality of extension pads 40 may be provided on thefirst surface 50 a of the insulating layer 50. Accordingly, theplurality of first bonding pads 20 and the plurality of extension pads40 may be provided on the first surface 50 a of the insulating layer 50.In particular, the plurality of first bonding pads 20 may be provided onthe first region A1 of the first surface 50 a of the insulating layer50, and the plurality of extension pads 40 may be provided on the secondregion A2 of the first surface 50 a of the insulating layer 50. Thefirst region A1 and the second region A2 may be regions separated fromeach other based on the center line Lc1 parallel to the first direction(x-axis direction) on the first surface 50 a of the insulating layer 50.Accordingly, the plurality of first bonding pads 20 and the plurality ofextension pads 40 may be separated from each other in the seconddirection (y-axis direction).

Referring to FIG. 1, the bonding layer 200 may be provided between theplurality of first bonding pads 20 and the electrode pads 10, andbetween the plurality of extension pads 40 and the electrode pads 10.The bonding layer 200 may have a single layer shape formed tosimultaneously contact the plurality of first bonding pads 20 and theplurality of extension pads 40. However, the present example embodimentis not limited thereto, that is, the bonding layer 200 may include afirst bonding layer and a second bonding layer separately formed fromeach other. For example, the first bonding layer may be provided betweenthe plurality of first bonding pads 20 and the plurality of electrodepads 10. In other words, the first bonding layer may be provided only ina region corresponding to the first region A1. Also, the second bondinglayer may be provided between the plurality of extension pads 40 and theplurality of electrode pads 10. In other words, the second bonding layermay be provided in a region corresponding to only the second region A2.

Referring to FIG. 1, each of the plurality of extension pads 40 on thefirst surface 50 a may be connected to each of the second bonding pads30 provided on the second surface 50 b through vias 51 included in theinsulating layer 50. In other words, the insulating layer 50 may includea plurality of vias 51 that connect the plurality of second bonding pads30 and the plurality of extension pads 40 in one-to-one correspondence.The plurality of vias 51 may be provided in an edge of the second regionA2 of the insulating layer 50. For example, the plurality of vias 51 maybe formed in an edge of the insulating layer 50 to be separated from aboundary line where the first area A1 contacts the second area A2 withthe plurality of extension pads 40 therebetween. A conductive material52 may be filled in the plurality of vias 51. For example, the pluralityof vias 51 may be filled with copper Cu. However, the present exampleembodiment is not limited thereto, that is, the plurality of vias 51 maybe filled with a conductive material 52 other than copper Cu. A furtherspecific arrangement of the bonding pad unit 310 will be described laterwith reference to FIG. 3.

FIG. 3 is a perspective view briefly showing an enlarged area C of FIG.1.

Referring to FIG. 3, the bonding pad unit 310 may include a plurality offirst bonding pads 20 and a plurality of extension pads 40 provided onthe first surface 50 a of the insulating layer 50. Also, the bonding padunit 310 may include a plurality of second bonding pads 30 provided onthe second surface 50 b of the insulating layer 50.

The plurality of first bonding pads 20 may be arranged to be parallel toeach other in the first direction (x-axis direction) at a positioncorresponding to the first region A1 (refer to FIG. 2) on the firstsurface 50 a of the insulating layer 50. The plurality of second bondingpads 30 may be arranged to be parallel to each other in the firstdirection (x-axis direction) on the second surface 50 b of theinsulating layer 50. The plurality of second bonding pads 30 may beformed to be included in both regions corresponding to the first regionA1 (refer to FIG. 2) and the second region A2 (refer to FIG. 2).Accordingly, the length of the plurality of second bonding pads 30 inthe second direction (y-axis direction) may be greater than that of theplurality of first bonding pads 20 in the second direction (y-axisdirection). The plurality of extension pads 40 may be arranged to beparallel to each other in the first direction (x-axis direction) at aposition corresponding to the second region A2 (refer to FIG. 2) on thefirst surface 50 a of the insulating layer 50.

As described above, when seen on a plan view of the printed circuitboard 300 (z-axis direction), the plurality of first bonding pads 20 andthe plurality of second bonding pads 30 may be alternately arranged witheach other in the first direction (x-axis direction). Accordingly, theplurality of first bonding pads 20 and the plurality of second bondingpads 30 that are provided on different surfaces of the insulating layer50 may be arranged in a zigzag shape on a side view in the seconddirection (y-axis direction) of the insulating layer 50.

The plurality of extension pads 40 may be arranged in one-to-onecorrespondence to the plurality of second bonding pads 30. For example,when seen on a plan view of the printed circuit board 300 (z-axisdirection), the plurality of second bonding pads 30 and the plurality ofextension pads 40 may be arranged to overlap each other. In other words,when seen on a plan view of the printed circuit board 300 (z-axisdirection), the plurality of second bonding pads 30 and the plurality ofextension pads 40 may be located on the same line in the seconddirection (y-axis direction) crossing the first direction (x-axisdirection). Accordingly, the plurality of first bonding pads 20 and theplurality of extension pads 40 may be arranged in a zigzag shape basedon the center line Lc1 of FIG. 2. As described above, the plurality ofsecond bonding pads 30 and the plurality of extension pads 40 may beelectrically connected to each other through the vias 51 included in theinsulating layer 50.

The plurality of first bonding pads 20, the plurality of second bondingpads 30, and the plurality of extension pads 40 may include a conductivematerial. For example, the plurality of first bonding pads 20, theplurality of second bonding pads 30, and the plurality of extension pads40 may include copper Cu. However, the present example embodiment is notlimited thereto, that is, the plurality of first bonding pads 20, theplurality of second bonding pads 30, and the plurality of extension pads40 may include a conductive material other than copper Cu. Each of theplurality of first bonding pads 20, the plurality of second bonding pads30, and the plurality of extension pads 40 may be covered with aconductive coating layer. The conductive coating layer may include, forexample, tin Sn. However, the present example embodiment is not limitedthereto, that is, the conductive coating layer may include a conductivematerial other than tin Sn.

FIG. 4 is a lateral cross-sectional view briefly showing a cross-sectiontaken along the center line Lc1 of FIG. 2. The plurality of extensionpads 40 are illustrated with a dashed line to be easily distinguishedfrom the plurality of first bonding pads 20. For convenience ofdescription, the vias 51 connecting the plurality of second bonding pads30 and the plurality of extension pads 40 are omitted in FIG. 4.

Referring to FIG. 4, the bonding pad unit 310 may include the pluralityof first bonding pads 20 and the plurality of extension pads 40 providedon the first surface 50 a of the insulating layer 50. The bonding padunit 310 may include the plurality of second bonding pads 30 provided onthe second surface 50 b of the insulating layer 50. The plurality offirst bonding pads 20 may have a width W in a range of about 15 μm toabout 35 μm. Furthermore, widths W of the plurality of first bondingpads 20, the plurality of second bonding pads 30, and the plurality ofextension pads 40 may all be the same. As described above, the firstbonding pad 20 and the second bonding pad 30 may be alternately arrangedin the first direction (x-axis direction). In this case, a separationdistance p between the first bonding pad 20 and the second bonding pad30 adjacent to each other may be in a range of about 15 μm to about 35μm.

FIG. 5 is a plan view briefly illustrating an example configuration ofan electrode pad unit 121 that may be included in the touch panel 100 ofFIG. 1.

Referring to FIG. 5, the electrode pad part 121 may include a pluralityof electrode pads 11. The plurality of electrode pads 11 may be arrangedto be parallel to each other in the direction of the center line Lc2 ofthe electrode pad portion 121. The direction of the center line Lc2 maybe a direction to be parallel to the first direction (x-axis directionin FIG. 2). Also, the plurality of electrode pads 11 may be provided onthe same plane. For example, the plurality of electrode pads 11 may beprovided on the same plane on the substrate sub of FIG. 1. Furthermore,the plurality of electrode pads 11 may be arranged in a zigzag shapebased on the center line Lc2 on the surface of the electrode pad unit121. For example, a part of the plurality of electrode pads 11 may bearranged on a lower side based on the center line Lc2, and another partof the plurality of electrode pads 11 may be arranged on an upper sidebased on the center line Lc2. Two alignment marks Ak3 may be provided inboth ends of the electrode pad unit 121. For example, the two alignmentmarks Ak3 may be arranged to be separated from each other with theplurality of electrode pads 11 arranged to be parallel to each other inthe first direction (x-axis direction in FIG. 2) therebetween. Also, twoalignment marks Ak3 may be provided on the center line Lc2 of theelectrode pad unit 121.

FIG. 6 is a lateral cross-sectional view briefly showing an exampleconfiguration of the sensing unit 110 of FIG. 1. For convenience ofdescription, in FIG. 6, it is depicted only a case in which one of theplurality of first electrodes Tx and one of the plurality of secondelectrodes Rx are crossed. The configuration illustrated in FIG. 6 maybe applied to all intersections between the plurality of firstelectrodes Tx and the plurality of second electrodes Rx.

Referring to FIG. 6, the sensing unit 110 may include a first electrodeTx and a second electrode Rx provided on a substrate 61. The firstelectrode Tx and the second electrode Rx may be provided on the sameplane on the substrate 61. The substrate 61 may be replaced with thesubstrate sub of FIG. 1. The first electrode Tx may be electricallyseparated from the second electrode Rx. For example, the first electrodeTx may have a bridge shape at a point where the first electrode Tx andthe second electrode Rx cross. The bridge shape may be formed to beseparated from the second electrode Rx. As shown in FIG. 6, the bridgeshape may include a straight line shape. However, the present exampleembodiment is not limited thereto, that is, the bridge shape may includea shape bent in a curved shape over the second electrode Rx.Accordingly, the first electrode Tx and the second electrode Rx may beprovided on the same plane on the substrate 61 and, at the same time,electrically separated from each other. Furthermore, the sensing unit110 may further include a protective layer 62 covering the firstelectrode Tx and the second electrode Rx. The protective layer 62 mayprevent the first electrode Tx and the second electrode Rx from beingdamaged by covering the first electrode Tx and the second electrode Rx.

FIG. 7 is a lateral cross-sectional view briefly showing an exampleconfiguration of the sensing unit 110 of FIG. 1, according to anotherexample embodiment.

A sensing unit 111 may include a first electrode Tx and a secondelectrode Rx provided on a substrate 71. The first electrode Tx and thesecond electrode Rx may be provided on different planes on the substrate71. For example, the second electrode Rx may be formed by directlycontacting a surface of the substrate 71. Furthermore, an insulatinglayer 72 may be provided on the second electrode Rx. The first electrodeTx may be provided on the insulating layer 72. In other words, the firstelectrode Tx may be formed by directly contacting a surface of theinsulating layer 72. In this way, the first electrode Tx is provided onthe insulating layer 72 and the second electrode Rx is provided on alower surface of the insulating layer 72, and thus, the first electrodeTx and the second electrode Rx are provided on different layers fromeach other. The sensing unit 111 may further include a protective layer73 covering the first electrode Tx. The protective layer 73 may preventthe first electrode Tx from being damaged by covering the firstelectrode Tx.

FIG. 8 is a lateral cross-sectional view schematically showing anexample configuration of a display device 2000 according to an exampleembodiment.

Referring to FIG. 8, the display apparatus 2000 may include a touchsensor 1000 including a touch panel that detects a user's touch and adisplay panel 1100 that is provided under the touch sensor 1000 totransmit an image. The touch sensor 1000 may be substantially the sameas the touch sensor 1000 described with reference to FIGS. 1 to 7.

The display panel 1100 may include any one of a liquid crystal panel andan organic light-emitting diode panel. However, the present exampleembodiment is not limited thereto, that is, the display panel 1000 mayinclude various types of image generating devices to transmit an image.As depicted in FIG. 8, the display panel 1100 may be provided under thetouch sensor 1000. For example, the display panel 1100 may be providedto correspond to a lower side of the sensing unit 110 (refer to FIG. 1)included in the touch sensor 1000. Accordingly, an image from thedisplay panel 1100 may be provided to a user through the transparentsubstrate sub included in the sensing unit 110.

The display device 2000 may further include a window 1300 on the touchsensor 1000 to protect the touch sensor 1000. The window 1300 mayprotect the touch sensor 1000 from external impact.

The display device 2000 may further include a polarizing film 1200provided between the window 1300 and the touch sensor 1000. Thepolarizing film 1200 may transmit light of an image transmitted from thedisplay panel 1100 and transmitted through the touch sensor 1000 in acertain direction. For example, the polarizing film 1200 may includeeither a circular polarizing film or a linear polarizing film.

According to the present disclosure, a touch sensor having a structurecapable of a large area may be provided.

According to the present disclosure, a touch sensor including a printedcircuit board including a bonding pad having a small pitch may beprovided.

The foregoing exemplary embodiments are merely exemplary and are not tobe construed as limiting. The present teaching can be readily applied toother types of apparatuses. Also, the description of the exemplaryembodiments is intended to be illustrative, and not to limit the scopeof the claims, and many alternatives, modifications, and variations willbe apparent to those skilled in the art.

What is claimed is:
 1. A touch sensor comprising: a touch panelcomprising a plurality of electrodes and a plurality of electrode padsrespectively connected to the plurality of electrodes; a bonding layerdisposed on and in contact with the plurality of electrode pads; and aprinted circuit board comprising: an insulating layer comprising a firstsurface adjacent to the bonding layer and a second surface facing thefirst surface; a plurality of first bonding pads provided only in afirst region of the first surface of the insulating layer; a pluralityof second bonding pads disposed on the second surface of the insulatinglayer; and a plurality of extension pads disposed only in a secondregion different from the first region of the first surface of theinsulating layer and respectively connected to the plurality of secondbonding pads, wherein on a plan view of the printed circuit board, theplurality of first bonding pads and the plurality of second bonding padsare alternately arranged in a first direction, wherein the first regionand the second region are separated from each other based on a centerline that is parallel to the first direction on a surface of theinsulating layer such that the plurality of first bonding pads and theplurality of extension pads are separated from each other in a seconddirection crossing the first direction, wherein the insulating layercomprises a plurality of vias that connect the plurality of secondbonding pads to the plurality of extension pads via a one-to-onecorrespondence, the plurality of vias disposed on an edge separated froma boundary line where the first region and the second region contacteach other with the plurality of extension pads therebetween, whereinthe first bonding pad and the extension pad contact the other surfacefacing the surface of the bonding layer contacting the plurality ofelectrode pads, wherein the plurality of extension pads extend in thesecond direction towards the plurality of first bonding pads such thateach of the plurality of extension pads has an extended part disposedbetween each of the plurality of vias and the first region, and anon-extended part connecting to each of the plurality of vias, andwherein the bonding layer contacts the extended part of each of theplurality of extension pads and does not contact the non-extended partof each of the plurality of extension pads, such that the bonding layerdoes not cover the plurality of vias.
 2. The touch sensor of claim 1,wherein the plurality of first bonding pads and the plurality ofextension pads are arranged in a zigzag shape with respect to the centerline.
 3. The touch sensor of claim 1, wherein on the plan view of theprinted circuit board, the plurality of second bonding pads and theplurality of extension pads are located on a same line in a seconddirection that is perpendicular to the first direction.
 4. The touchsensor of claim 1, wherein the plurality of second bonding pads areincluded in all regions corresponding to the first region and the secondregion.
 5. The touch sensor of claim 1, wherein the plurality of viasare filled with a conductive material.
 6. The touch sensor of claim 1,wherein the plurality of electrode pads are disposed on a same plane. 7.The touch sensor of claim 1, wherein the plurality of electrode pads arearranged to be parallel to each other in the first direction.
 8. Thetouch sensor of claim 1, wherein the plurality of electrode pads arearranged in a zigzag shape based on the center line that is parallel tothe first direction.
 9. The touch sensor of claim 1, wherein on the planview of the printed circuit board, a separation distance between thefirst bonding pads and the second bonding pads adjacent to each other isin a range of 15 μm to 35 μm.
 10. The touch sensor of claim 1, whereinthe bonding layer comprises an anisotropic conductive film layer. 11.The touch sensor of claim 1, wherein the bonding layer comprises a firstbonding layer and a second bonding layer that are separated from eachother, wherein the first bonding layer is disposed between the pluralityof first bonding pads and the plurality of electrode pads, and thesecond bonding layer is disposed between the plurality of extension padsand the plurality of electrode pads.
 12. The touch sensor of claim 1,wherein the printed circuit board comprises either one or both of a chipon film (COF) and a flexible printed circuit board (FPCB).
 13. The touchsensor of claim 1, wherein the plurality of electrodes and the pluralityof electrode pads are arranged on a substrate including at least one ofglass and film.
 14. The touch sensor of claim 1, wherein the pluralityof electrodes comprises: a plurality of first electrodes extending inthe first direction and arranged to be parallel to each other in thesecond direction perpendicular to the first direction; and a pluralityof second electrodes extending in the second direction to cross theplurality of first electrodes and disposed to be parallel to each otherin the first direction.
 15. A display device comprising: the touchsensor of claim 1; and a display panel disposed on a lower side of thetouch panel.